Gradient index single lens

摘要

A gradient index single lens has a first surface convex toward the object side, the first surface lying on the object side when the lens is used at a reduction magnification, a second surface concave toward the image side, the second surface lying on the image side when the lens is used at a reduction magnification, and an index distribution formed in the interior of the lens, the index distribution having a sphere symmetrical distribution about a certain point on the optic axis.